As a conventional method of electrochemically analyzing a biological fluid using a microchip, a biosensor for analyzing a specific component in a liquid sample obtains, for example, a blood glucose level and so on by measuring a current value obtained from the reaction of glucose in blood and a reagent, such as glucose oxidase, supported in the sensor.
As a method of optically analyzing a biological fluid, a method of analyzing a biological fluid using a microchip having liquid channels formed thereon is known. This microchip, capable of controlling a fluid using a rotary device having a horizontal shaft, can weigh liquid samples, separate cytoplasmic materials, transfer and distribute the separated fluids, mix/stir liquids, and the like, by using centrifugal force. This makes it possible to perform a variety of biochemical analyses.
As a conventional method of collecting a liquid sample, a centrifugal transfer biosensor, shown in FIG. 12, is disclosed in Patent Document 1. This centrifugal transfer biosensor has a plurality of cavities having different depths formed in a container 310. A liquid sample is collected into a first capillary cavity 312 through an inlet 313 by capillary action, and then the liquid sample in the first capillary cavity 312 is transferred to a receiving cavity 317 through a filtering material 315 and a first channel 314 under the action of centrifugal force. Then, after the liquid sample reacts with a reagent and is centrifuged in the receiving cavity 317, only a solution component of the liquid sample is collected in a second capillary cavity 316 by the capillary force of a core 318, and the reaction state of the liquid sample is read optically.
Further, another centrifugal transfer biosensor, shown in FIG. 13, is disclosed in Patent Document 2. FIG. 13 shows a distribution unit 400. An inlet port 409 is connected to a capillary cavity 404a through an upper part 402. The capillary cavity 404a is connected to a capillary cavity 404b through a conduit 405a. Similarly, the capillary cavity 404 band capillary cavities 404c, 404d, 404e, and 404f are connected sequentially through conduits 405b, 405c, 405d, and 405e. The capillary cavity 404f is connected to an outlet port 410 through an upper part 403. Air vents 406a, 406b, 406c, 406d, 406e, 406f, and 406g are provided at the upper part 402, the conduits 405a, 405b, 405c, 405d, and 405e, and the upper part 403, respectively. A liquid sample introduced through the inlet port 409 is transferred to the outlet port 410 by capillary force to fill the capillary cavities 404a, 404b, 404c, 404d, 404e, and 404f with the liquid sample. By centrifugal force generated by the rotation of the biosensor, the liquid sample in the capillary cavities 404a, 404b, 404c, 404d, 404e, and 404f is then distributed at the air vents 406a, 406b, 406c, 406d, 406e, 406f, and 406g, and is transferred to a subsequent treatment chamber (not shown) through valves 408a, 408b, 408c, 408d, 408e, and 408f and connecting microconduits 407a, 407b, 407c, 407d, 407e, and 407f, correspondingly.    Patent Document 1: Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 4-504758    Patent Document 2: Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2004-529333